1. Field of the Disclosure
The present disclosure relates in general to lift trucks, forklifts, front-end loaders, pallet jacks, and the like, that use a movable assembly to maneuver a load. Embodiments disclosed herein generally relate to a fail-safe system whereby a load-bearing portion of a lift truck is placed in a safe position, and/or the lift truck is inoperable when a load is not present on the load-bearing portion. Other embodiments pertain to a safety system that defaults a configuration of a lift truck to a safety configuration.
2. Background Art
It has long been known to employ a lift truck (e.g., a forklift), for the movement of loads and other objects found in industrial locations, warehouse settings, and other various applications. Although lift trucks are available in a multitude of sizes, types, and configurations, nearly all are characterized by a movable assembly and/or “mast” upon which an attached fork or other load-bearing member is supported. Elevational movement of the assembly is often achieved by controlled operation of an hydraulic ram and/or a piston-cylinder mechanism. Thus, typical use of a lift truck not only includes movement of loads between various locations, but various heights as well.
Referring to FIG. 1, a perspective view of a conventional lift truck 100 is shown. The lift truck 100 includes a frame or body 136 connected with a motorized mover 102, and there is an operator's workspace 152 that may include features such as a seat and steering wheel. A plurality of rails or guides 138 are usually connected to the frame 136 and/or motorized mover 102, with a corresponding front-end assembly 103 movably connected to the rails 138 in such a way that the front-end assembly 103 may move up, down, sideways, etc.
The front-end assembly 103 may include a mast 103a, as well as a lifter element 118. The lifter element 118 may take a number of configurations, but typically includes L-shaped forks 139 (i.e., tines, etc.) that are coupled to the mast 103a. The fork usually has a vertical portion 112 that abuts and/or is attached to the mast 103a. The fork 139 also includes a forwardly extending, generally horizontal leg 113 that constitutes the load-bearing portion of a lifter element 118. Together the forwardly extending forks 139 are used to lift load(s) 140 vertically relative to the motorized mover 102.
A typical lift truck 100 has at least one ram cylinder-piston mechanism 146 for lifting and lowering a fork and/or the mast assembly, such that movement of the front-end assembly may be controlled by the ram cylinder-piston mechanism 146. As is known in the art, the lift truck has a working configuration 105, whereby the forks 139 may be inserted within a pallet 144 which supports the load 140 and/or 144, and the forks 139 may thereafter be lifted to raise the pallet 144 and load 140 for movement. Hence, as the mast 103a moves, so may the load 140 disposed on the lifting element 118. The front-end assembly 103 may move, for example, up or down with respect to the motorized mover 102.
However, the use of the lift truck may be problematic and inherently dangerous. For example, whether stationary or in transit, fork(s) or other lifter members extend awkwardly outward into open space. This is extremely dangerous and has resulted in serious injury and death as a result of impact with operators, other workers, passersby, etc. The danger of the forks is exacerbated by the fact that the forks can be elevated. The extended forks also require a wide turn radius in order to not inadvertently run into people and objects. The need for improved safety in lift truck operation(s) is exemplified by the following description.
Even more problematic is that an operator has to focus on the task of operating and driving the lift truck (with or without load) often forgetting about, or losing track of, the elevation of the forks, such that the forks impact people or other items. Lift trucks are an essential part of most industrial and supply chains around the world. However, statistics indicate that lift trucks also present significant hazards to people occupying the same workspace, and lift truck induced injuries may be severe or fatal. While lift trucks are a major cause of industrial deaths and accidents, little has changed in lift truck operations to reduce the rate of incidents that occur as a result of lift truck usage.
As presented by a National Institute for Occupational Safety and Health (NIOSH) report, lift trucks strike people everyday, resulting in 100 deaths and over 20,000 injuries annually in the United States Alone. The NIOSH report shows that approximately every 3 days, someone in the US is killed in a lift truck related accident. Each year, an additional 94,750 injuries related to forklift accidents are reported. Besides workman's compensation and/or lost time at the job, there are huge lawsuits awarded for lift truck accidents. The costs incurred as a result of lift truck accidents are estimated to be in excess of $100 million dollars US annually.
Additionally, lift trucks cause damage to material. Recent events include the shut down of a busy North Carolina port after a lift truck operator accidentally punctured containers of pentaerythritol tetranitrate (PETN), the same chemical used in a Christmas Day airline bombing attempt. Not only is there an expenditure of a massive amount of resources to clean up spilled materials, but accidents such as these cause concern about acts of domestic terrorism. This leads to additional expenditure of resources, like involvement by the Department of Homeland Security, increased security at airports, etc., each of which having an unrelenting domino effect on an entire portion of the national economy.
The use of conventional lift trucks is problematic, and as a consequence, the use of lift trucks, especially in small or tight spaces, is difficult, inconvenient, and dangerous. As such, there has long been a chronic need in the use of lift trucks (or other comparable material handling equipment) for a safety system that can be used to reduce or eliminate the risk of serious injury and death to people. There is a need for a safety system that may be employed rapidly and dependably, and even automatically, that includes moving the front-end assembly to an out-of-the-way position. These needs are prevalent on new and existing lift trucks, such that there is a need to retrofit existing lift trucks with a safety system.
There are additional needs for a lift truck capable of a smaller turning radius that results from the forks/blades being retracted/stored/moved to an out-of-the-way position. There is also a need for a lift truck that has a considerably smaller “footprint” during storage and non-load bearing travel. There is a chronic need for the prevention of injuries and loss of life associated with load and non-load bearing travel. There is a comparable need for the prevention of loss of material and property damage associated with non-load bearing travel.